The binding of antibodies to target antigens, which are bound to cells, is a fundamental reaction in all fields of serology and especially of clinical diagnostics. Such binding can be determined by various methods. These methods include the observation of the cell agglutination by the antibodies, the cytotoxicity test, as well as a variety of methods in which there are used labelled antibodies, the presence of which on the cell surface is ascertained by other methods, for example, by radioactivity measurement, by determination of the enzyme substrate reaction as well as by fluorescence measurement. In German Offenlegungsschrift No. 2907198 there is described a sensitive method for the detection of the binding of antibodies to erythrocytes (RBC), which is based on the adherence of the antibody-loaded RBC to a plastic surface. According to this method, the target antigen (A), which is carried by the RBC, reacts with a specific antibody of serum or cells of an animal species X (X-anti-A). After a washing operation, in which excess X-anti-A is removed, there is added a further anti-serum (B) which has a specificity against the determinants of the immunoglobulins of X-anti-A. After a further washing step, the cells are centrifuged in a cuvette, the V-shaped body of which is loaded with immunoglobulin (Ig) of the animal species X(IgX). The cell-bound antibodies (B) have free binding positions, which bind with the IgX, from which there results an adherence of the cells to the plastic material. In the case of a negative reaction, where no anti-A is bound to the cell surface, anti-serum B likewise does not bind, and no adherence of the cells results during the centrifugation. The method described in the aforementioned DOS has two disadvantages, namely:
(a) the requirement of the repeated cell washing steps, which are time-consuming, and PA0 (b) the dependence on a defined, critical concentration of X-anti-A on the cell surface, to the extent that just the same as before anti-X binding positions of the cell-bound antiserum (B) are present for the binding of IgX to the plastic surface.
In accordance with the present invention an immunoglobulin-binding component is bound directly to the plastic material of the cuvette and can thus be used in the adherence test for the detection of X-anti-A, which are bound to the cells. In this manner washing steps are eliminated, and the sensitivity of the test is increased.